European Project NANO-CATHEDRAL: Nanomaterials for conservation of European architectural heritage developed by research on characteristic lithotypes

The project NANO-CATHEDRAL aims at developing new materials, technologies and procedures for the conservation of deteriorated stones in monumental buildings and cathedrals and high value contemporary architecture, with a particular emphasis on the preservation of the originality of materials and on the development of a tailor-made approach to tackle the specific problems related to the different lithotypes. In fact, the objective is providing “key tools” in terms of innovative nano-structured conservation materials, for restoration and conservation on a full European scale, thanks to the research work made onto lithotypes representative of different European geographical areas and styles and of different climate and environmental conditions. Five different cathedrals were selected as they may be considered as representative of both different exposure conditions and different types of stones. In particular, the Cathedral of Pisa, in central Italy, and the Cathedral de Santa María of Vitoria-Gasteiz in Spain were selected as representative of south European “Mediterranean” climate in coastal and continental regions, respectively; the Sint-Baafs Cathedral of Ghent, in Belgium, the Cathedral of St. Peter and Mary in Cologne, Germany and the St. Stephen's Cathedral, in Wien, Austria, were selected as representative of North European climate in coastal and continental regions, respectively. Moreover, the Oslo Opera House, was considered as an example of a contemporary building coated with white Carrara marble. They also represent different lithotypes such as marble, sandstone, limestone. A general protocol has been defined for the identification of the petrographic and mineralogical features of the stone materials, the identification of the degradation patterns, the evaluation of the causes and mechanisms of alteration and degradation, including the correlations between the relevant state of decay and the actual microclimatic and air pollution conditions. At this stage, the project is focused on the characterization of innovative materials, such as nano-particle based consolidants, and proper polymer nano-composites based coatings to test onto stones. Efficacy ofselected products by proper measurements is under study, for verify the consolidation and protection action, and also their durability, making tests of accelerated aging. Dedicated modelling, tailored characterizations, standardization of the production and treatments application will be the next step activities of the NANO-CATHEDRAL project, aimed at enabling decision makers to access to restoration and conservation with a systematic awareness based on in situ systematic experimentations.